Wave transmission lines and networks – Plural channel systems – Nonreciprocal gyromagnetic type
Reexamination Certificate
1998-11-06
2003-01-07
Bettendorf, Justin P. (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Nonreciprocal gyromagnetic type
C333S024200, C333S219100
Reexamination Certificate
active
06504444
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
The present invention claims priority from Japanese Patent Application No.9-306011 filed Nov. 7, 1997, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a micro wave integrated circuit (MIC) having a plurality of circuit parts mounted on a ceramic substrate and a method for manufacturing the same integrated circuit. The present invention is utilized in a communication equipment, radar, measuring equipment or other equipment. Particularly, the present invention is utilized in a filter circuit, an isolator, a transmission/receiving separating circuit, an antenna circuit or other circuits of this type of equipment. Although the present invention was developed for utilization thereof in a high frequency circuit operating at a frequency exceeding 10 GHz, the utilizing frequency is not limited thereto and the present invention can be utilized in a circuit operating at a frequency higher than 10 GHz.
2. Description of Related Art
A technique for forming a micro wave integrated circuit having a plurality of circuit parts mounted on a ceramic substrate by soldering or ribbon or wire connection has been known. Although it is usual to form conductors of a circulator, among the circuit parts mounted on a ceramic substrate, on a soft ferrite substrate, Japanese Patent Application Laid-open No. Hei 61-288486 discloses a technique in which holes are formed in a green sheet of an alumina substrate which is to be sintered at low temperature, ferrite parts are fitted in these holes and the green sheet is sintered to fixedly secure the ferrite parts in the holes.
This technique is a useful technique in mounting ferrite parts in a ceramic substrate and the present invention is based on this technique. However, this technique is to form a circulator part by mounting a ferrite unit on a low temperature sintered alumina substrate and does not suggest a technique for arranging a plurality of mutually related circuit parts on a low temperature sintered alumina substrate to unify them as an integrated circuit. Further, the disclosed technique does not suggest a use of hard ferrite as the ferrite material and a magnetization of the hard ferrite correspondingly to circuit characteristics after sintering.
On the other hand, Japanese Patent Application Laid-open No. Hei 6-334413 of the same assignee as that of the present invention discloses a technique for unifying a high frequency filter as a monolithic micro wave integrated circuit. According to this technique, an insulating film is formed on a surface of a semiconductor substrate and conductor lines are formed on the insulating film. Further, a dielectric resonator is mounted in the vicinity of the conductor lines. The dielectric resonator is fitted in a recess formed in the insulating film.
However, according to this technique, it is impossible to unify a conventional circulator using soft ferrite.
On the other hand, a high frequency band exceeding 10 GHz has been used in various equipment. Particularly, a frequency of an automobile radar or a distance meter is assigned to a 60 GHz band or a 70 GHz band. Therefore, in view of limited space in which such a device is mounted, a technique for mass-producing a compact high frequency integrated circuit having uniform characteristics at low cost is required. In the conventional MIC technology, however, an area for connecting such parts as a circulator, high frequency filter and MMIC, etc., is necessary, with which there is a limitation in reducing the size of the device.
In reducing the size of the device, the conventional technique is basically superior in forming a high frequency filter integrally with the MMIC. However, the integration of a conventional circulator with the MMIC is impossible in principle since the conventional circulator requires an external magnet. Further, in order to obtain uniform characteristics according to the conventional MIC technology, the parts themselves must have stable characteristics. Even if such parts are obtained, loss which can not be considered in the design stage of the device may occur in connecting portions of the parts and it is impossible to control such loss, so that there may occur variation of characteristics between substrates. Therefore, it is necessary to regulate the characteristics of the device after it is assembled, the number of working steps is increased and skilled workers are necessary for the regulation of the characteristics of the device.
SUMMARY OF THE INVENTION
The present invention was made in view of the above background and has an object to provide a micro wave integrated circuit (MIC) including dielectric parts and magnetic parts both formed on a single substrate and a method for manufacturing the same.
Another object of the present invention is to provide a reliable high frequency integrated circuit having substantially no power loss at connecting points which is the problem in the structure in which individual parts are connected and a method for manufacturing the same high frequency integrated circuit.
Another object of the present invention is to provide a high frequency integrated circuit which has stable characteristics and is capable of being manufactured uniformly and a method for manufacturing the same high frequency integrated circuit.
Another object of the present invention is to provide a high frequency integrated circuit capable of being manufactured with a small number of manufacturing steps and a method of manufacturing the same high frequency integrated circuit.
A further object of the present invention is to provide a high frequency integrated circuit which can be mass-produced at low cost and a method of manufacturing the same high frequency integrated circuit.
Another object of the present invention is to provide a high frequency integrated circuit which is suitable for use in designing and manufacturing a filter or an antenna circuit which can be utilized in several tens GHz frequency band and a method for manufacturing the same high frequency integrated circuit.
A further object of the present invention is to provide a high frequency integrated circuit whose electric characteristics can be reversibly regulated while monitoring the characteristics thereof after manufacture and a method for manufacturing the same high frequency integrated circuit.
According to a first aspect of the present invention, a high frequency integrated circuit is featured having a structure in which magnetic parts or magnetic parts and dielectric parts are unified in a single integrated circuit substrate and in which two or more of these circuit parts form desired high frequency characteristics. That is, a plurality of parts constructing an isolator, a circulator or a filter are constituted as a circuit having high frequency characteristics as a whole. A conductor pattern is formed on a surface of the ceramic substrate as lead lines of the circuit or as micro strip lines.
The magnetic parts may be of hard ferrite. The hard ferrite can be utilized as a constructive element of a circulator or an isolator. Further, the dielectric parts can be utilized as constructive elements of a high frequency filter. The dielectric substrate may be of organic material and, particularly, polytetrafluoroethylene is a suitable material thereof. The dielectric substrate is preferably a ceramic substrate.
According to a second aspect of the present invention, a method for manufacturing a high frequency integrated circuit, which is featured by comprising, in a case where the dielectric substrate is a glass ceramic substrate, the steps of forming a plurality of holes in a green sheet of the glass ceramic, fitting circuit parts in the respective holes, forming the ceramic substrate by sintering the green sheet at a temperature not higher than a temperature at which the circuit parts are deformed and not lower than a sintering temperature of the green sheet and fixedly securing the circuit parts in the ceramic substrate by utilizing the
Furuya Mitsuru
Myohga Osamu
Okada Yoshitsugu
Bettendorf Justin P.
Choate Hall & Stewart
NEC Corporation
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